Where I live it will often get to 140-150 F range in a car or truck cab, depending on the paint color of the vehicle and if it is parked in full sun. I have had some older scanner's display screen rendered useless by the heat. Just depends on the conditions but I don't think I'd chance it.
It is not unusual to see many devices with liquid crystal displays go black when they get warm. Fortunately they usually come back once cooled down. Excessive heat in the case of electronics usually equates to excessive wear, but, many of these devices were designed to be mobile so hopefully the manufacturers factored that in.
I had a brand new Uniden 100 channel scanner. Had it "properly" mounted. Out of the direct sunlight. Got hot one day & buckled the area just below the display. Just enough to cause a couple of the buttons to stick. Never hurt the display, just the surrounding plastic buckled. That was a real PAIN IN MY You know what!!!! Never affected the RX of the unit though. Just looked like heck!!! It was mounted in a full size 1988 Chevrolet Blazer. I still have it. Use it in the house though...Steve/KB8FAR